Abbreviation: DIS
A term most commonly used in multiple sclerosis that refers to the formation of demyelinating lesions in different anatomical regions within the CNS. It can be demonstrated either by objective clinical evidence of at least two distinct lesions (e.g., optic disc pallor and hemiparesis confirmed by neurological examination in a person who presents with monocular scotoma and limb weakness) or MRI evidence of at least one lesion seen in at least two different CNS regions (periventricular, juxtacortical, infratentorial, and/or spinal).